1. Field of the Invention
The present invention generally relates to vehicle speed control means and more particularly to an improved vehicle speed bump device.
2. Prior Art
Speed bumps are frequently embedded in roadways, such as in access lanes to and from residential and school areas, parking lots and the like so as to discourage or prevent the use of vehicles at high speed. Most such speed bumps are merely spaced rubber, steel or concrete bars or the like connected to the top of the road surface and, accordingly, are severly subject to wear. Moreover, they do not retract, so that even slow moving vehicles are jolted by passing over the bumps. See, for example, the speed bumps of U.S. Pat. Nos. 4,203,685, 4,697,294, 4,687,370, 4,362,424 and 3,720,181, some of which are of improved design but generally of the same basic type.
Certain other speed bumps have been devised, which bumps can be retracted or raised, as needed, either by a tool (see U.S. Pat. No. 4,012,156) or by a remotely operated hydraulic ram (see U.S. Pat. Nos. 4,342,525 and 4,490,068), the latter being expensive and complicated. However, none of such devices permit slow moving vehicles to pass thereover without a bump and simultaneously cause fast moving vehicles passing thereover to encounter a bump, in a cost-efficient manner.
Accordingly, there remains a need for an improved speed bump which can simultaneously allow slow moving vehicles to pass thereover smoothly without a bump but causes rapidly moving vehicles to suffer a bump. Such device should be simple, inexpensive, and durable, and require no periodic adjustments or repair. Such device would encourage the steady smooth flow of slow moving traffic.